Chapter 22

Nuclear chemistry

Objectives

  1. The Nucleus (section 22-1)
      1. Basic terms
        1. Nucleons- the particles that make up the nucleus. 1. _____ 2. _____
        2. Nuclide- means the atom identified by the number of nucleons 1.______2._______
      2. Mass Defect and Nuclear Stability
        1. Mass Defect- the difference between the mass of an atom and the mass of the atoms p, n, e.
          1. Electrons do have mass
          2. Mass is not counted

           

           

        2. Nuclear Binding Energy
          1. What causes the loss in mass?
          2. E= mc2
          3. Definition- the energy released when a nucleus is formed from nucleons.
          4. Amount of energy to split a nucleus
          5. a measure of the stability of the nucleus.
          6. Figure 2-1 pg 702
        3. Binding energy per nucleon
          1. Is used to compare the stability of nuclides
          2. Definition- is the binding energy of the nucleus divided by the number of nucleons it contains
      3. Nucleons and Nuclear Stability
        1. Band of stability- a range of neutron-proton ratios
          1. Low atomic numbers most stable
          2. Ratio of 1:1
          3. Above bismuth (83) no stable nuclides exist.
          4. Nuclear shell model- nucleons exist in different energy levels, or shells.
          5. 2,8,20,28,50,82,126 magic numbers
        2. Nuclear reactions
          1. Definition- is a reaction that affects the nucleus
            1. Mass numbers must equal
            2. Atomic numbers must equal
          2. Transmutation
            1. Definition-is a change in the identity of a nucleus as a result of a change in the number of protons.
            2. Practice pg 704

       

       

       

       

       

       

       

       

       

       

      Objectives:

    1. Define and relate the terms radioactive decay and nuclear radiation.
    2. Describe the different types of radioactive decay and their effects on the nucleus.
    3. Define the term half-life, and explain how it relates to the stability of a nucleus.
    4. Define and relate the terms decay series, parent nuclide, and daughter nuclide.
    5. Explain how artificial radioactive nuclides are made, and discuss their significance.
    6. Radioactive decay (section 22-2)
        1. Discovery
          1. 1896 Henri Bacquerel
          2. Made use of a photographic plate
          3. Radioactive decay – is the spontaneous disintegration of a nucleus into a slightly lighter nucleus, accompanied by emission of particles, electromagnetic radiation or both.
          4. Nuclear radiation- particles of electromagnetic radiation emitted from the nucleus during radioactive decay.

            5.  

          5. Marie Curie and Pierre Curie
            1. 1896 only uranium and thorium radioactive
            2. 1898 discovered polonium and radium
        2. Types of Radioactive Decay
          1. Depends on the content and energy level
          2. Table 22-1 Radioactive Nuclide emissions

            3. Type

            Symbol

            Charge

            Mass(amu)

             

             

             

             

             

             

             

             

             

             

             

             

             

             

             

             

          3. Alpha Emission

                1. Too many protons and neutrons
                2. Two protons and two neutrons
                3. Helium nucleus
                4. + 2 charge
          4. Beta Emission
                1. Too many neutrons
                2. Neutron converted to a proton and electron
                3. Electron is a Beta particle (b )
                4. An electron emitted from the nucleus
          5. Positron Emission
                1. Too many protons
                2. Proton converted into a neutron
                3. Has the same mass as an electron but a positive charge.
          6. Electron Capture
                1. Too many protons
                2. An inner orbital electron is captured by the nucleus.
          7. Gamma Emission
                1. Symbol (g )
                2. High-energy electromagnetic waves emitted form the nucleus
                3. Short wavelength
        3. Half-life
          1. No two decay at the same rate
          2. t ½- is the time it takes for half the atoms to decay.
          3. Table 22-2 Representative radioactive nuclides and their half-lives.
            4.

            Nuclide

            Half-life

            Nuclide

            Half-life

             

             

             

             

             

             

             

             

             

             

             

             

             

             

             

             

          4. Practice problems pg 709

        4. Decay Series
          1. Definition- is a series of radioactive nuclides produced by successive radioactive decay until a stable nuclide is reached.
          2. Parent nuclide- the heaviest in the series
          3. Daughter nuclide- all the nuclides produced.
          4. Figure 22-8
        5. Artificial Transmutations
          1. Definition- bombardment of stable nuclei with charged and uncharged particles
          2. Artificial radioactive nuclides- radioactive particles not found naturally on Earth.
          3. Particle accelerator – Fermi International Accelerator Laboratory.
          4. Transuranium elements- above 92 protons

         

         

         

         

        Objectives

      1. Compare the penetrating ability and shielding requirements of alpha particles, beta particles, and gamma rays.
      2. Define the terms roentgen and rem, and distinguish between them.
      3. Describe three devices used in radiation detection.
      4. Discuss applications of radioactive nuclides.
      5. Nuclear radiation (section 22-3)
          1. Radiation Exposure
            1. Roentgen- unit used to measure radiation
            2. rem (roentgen equivalent, man) the damage to human tissue
            3. About .1 rem per year
            4. Maximum is .5 rem per year
          2. Strength of particles
            1. Alpha- paper
            2. Beta- lead or glass
            3. Gamma- lead and or concrete
          3. Radiation Detection
            1. Film Badges- use exposure of film to measure the approximate radiation exposure of people
            2. Geiger-Muler counters-detect electric pulses carried by radioactive gas.
            3. Scintillation counters- converts scintillation light to electric signal.
          4. Applications of Radiation
            1. Radioactive dating- determining age
            2. Radioactive nuclides in medicine- cancer treatment and tracers
            3. Radioactive Nuclides in Agriculture- tracers used to test fertilizers
          5. Nuclear Waste
            1. Produced from nuclear fusion and fission.
            2. Containment of Nuclear waste-
              1. Depends on half-life
              2. Store currently at nuclear power plants
            3. Storage of Nuclear Waste-
              1. Spent fuel rods- stored in water
              2. Dry casks used after water pools
            4. Disposal of Nuclear Waste
              1. 77 disposal sites in U.S.
              2. Yucca Mountain near Las Vegas
              3. Transported by truck beginning in 2010
        1. Objectives
        2. Define nuclear Fission, Chain reaction, and nuclear fusion, and distinguish between them.
        3. Explain how a fission reaction is used to generate power.
        4. Discuss the possible benefits and the current difficulty of controlling fusion reactions.
        5. Nuclear Fission and Nuclear Fusion ( Section 22-4)
            1. Nuclear Fission- a very heavy nucleus splits into more-stable nuclei of intermediate mass.
              1. Can occur spontaneously
              2. Can be bombarded
            2. Nuclear Chain Reaction- is a reaction in which the material that starts the reaction is also one of the products and starts another reaction.
              1. Critical mass- the minimum amount of nuclide that provides the number of neutrons needed to sustain a chain reaction.
              2. Nuclear reactors- use controlled fission chain reactions to produce energy.
            3. Nuclear Power Plants
              1. Use heat from nuclear reactors to produce electrical energy
              2. Five components
                1. Shielding- radiation absorbing material
                2. Fuel- uranium-235
                3. Control rods- neutron absorbing rods that help control the reaction.
                4. Moderator- slows the fast neutrons
                5. Coolant- keeps it from blowing up.
              3. Nuclear Fusion-
                1. Definition- Light-mass nuclei combine to form a heavier, more stable nucleus.
                2. Releases even more energy than fission
                3. Occurs in the sun
                4. Two hydrogen nuclei atoms combine to produce hydrogen.
                5. The hydrogen bomb-trigger a fission bomb
                6. Problems initial temp. 108K